The United States Environmental Protection Agency (“EPA”) regulates particulate matter air pollution in the United States. More specifically, the EPA sets air quality standards regarding two size categories of particulate matter, PM10 and PM2.5 (40 CFR §§50.6 and 50.7). Compliance with these (and other) EPA air quality standards may require removal of at least some PM10 and/or PM2.5 particulate matter from a gas stream.